These white, or pinky looking spots are simply viral dermatitis (Lymphocystis) - or Carp Pox as it is normally called in the UK, whatever name you apply; and these lesions seem to only respond to warm water..

Rumor has it that any Koi with a white pox lesion which is placed in a heated pond (and very slowly and always well aerated) bring it up to 85 degrees and you will see sudden, rapid and complete remission of these viral skin lesions. There are apparently no exceptions, (it works on viral lesions of all types) immediately, with no waiting. And that's all you need. 

You can always salt the pond if you wish or even give the individual fish a salt bath, and you can do the other things with no harm. But white waxy lesions in fins and tail should not be scraped off as this will only result in bleeding where the carp pox has been removed and this could cause a secondary infection to set in. (in the absence of body sores or other pathology), 

Lymphocystis can be confirmed with a microscope, the cells are huge and foamy looking.